textproduct: Albany

WHAT HAS CHANGED

The Storm Prediction Center has shifted the Marginal Risk (Level 1 of 5) for severe weather for today slightly further north, as now covers parts of southern Greene, Ulster, Dutchess and Litchfield Counties. WPC has also included parts of the eastern Catskills in a Slight Risk (Level 2 of 4) for Excessive Rainfall for today as well.

While our area is not outlooked for any severe weather on Saturday, there continues a Marginal Risk (Level 1 of 4) for Excessive Rainfall across the entire area for Saturday.

KEY MESSAGES

1) Scattered to numerous showers and thunderstorms are expected again through the late evening hours, bringing the potential for locally heavy rain and isolated damaging wind gusts.

2) The combination of warm temperatures and very humid conditions will continue today, which will result in a risk for heat-related impacts, especially in eastern Ulster, western Dutchess and southern Litchfield CT.

DISCUSSION

KEY MESSAGE 1...

Similar to the past few days, our region remains a warm and humid air mass on the western side of the Bermuda High. Temperatures has reached well into the 80s for most the region with dewpoints in the 60s to low 70s. Although PWATs are slightly lower today compared to yesterday on the 12z KALY sounding (1.62" vs. 1.90" last evening), they remain above- normal. Latest SPC mesoanalysis shows abundant instability in place, with MLCAPE values around 1000 J/kg, with locally around 1500 J/kg across far southern areas. Even higher instability is located south of the region over eastern PA and NJ. Mid-level lapse rates are a little higher compared to yesterday due to approaching height falls (around 6 deg C/km), but this is still isn't too impressive at this time. 0-6 km bulk shear is generally only around 20 kts or so, so not too high either.

Although there is a subtle upper level disturbance moving across the eastern Great Lakes, overall large-scale forcing is rather weak and the nearest surface boundary is well west of the area over the Midwest. Still, this disturbance has been enough to allow for some scattered showers and thunderstorms to develop west and southwest of the region over central NY and especially central and eastern PA, where some severe storms have been ongoing. While the 3km HRRR doesn't seem to be handling this activity very well at the moment, radar trends would suggest that the bulk of this activity may slide south of the region. However, southern areas (such as the Catskills, mid Hudson Valley, Taconics, and parts of western New England), could be impacted by some of this activity later this afternoon and into this evening. Isolated damaging wind gusts can't be ruled out due to the unstable environment, but the weak lapse rates and limited large-scale forcing should keep severe storms from being overly widespread.

The other threat will be locally heavy downpours. Similar to yesterday, the humid air mass will be capable of producing heavy downpours in a short period of time, with 1 to 2 inches of rainfall easily falling in any thunderstorm. If this occurs over an urban area or location that has seen recent rainfall, it could quickly cause a flash flood. Will need to monitor radar trends through this evening for any flash flood potential, especially if storms repeat over the same areas. At this time, southern areas may be most as risk based on radar trends, but really can't rule it out for anywhere in the forecast area. Storms should wind down by the late evening hours with the loss of daytime heating and the threat for flooding downpours will be done by midnight or so.

On Saturday, there may again be the threat for isolated storms, although coverage looks lower than today. 0-6 km bulk shear will continue to be on the lower side on Saturday (mainly under 30 kts), although it will continue to be rather warm and muggy. Isolated wind damage or a isolated flash flooding cannot be ruled out once again, but the sparser storm coverage should keep these threats more limited for Saturday. The main time window for Saturday will be afternoon into the early evening hours based on the latest CAMs. Luckily, drier weather is expected for Sunday, with no threat for strong/severe storms or flooding downpours for Sunday at this time.

KEY MESSAGE 2...

Heat Advisory continues through 8 pm this evening for eastern Ulster, western Dutchess and southern Litchfield Counties. Dewpoints remain near 70 in these areas, with afternoon temps reaching the mid to upper 80s. This should allow for heat index to exceed 95 degrees for a few hours for the mid afternoon through early evening hours. Residents and visitors should practice heat safety, and take breaks in the shade and drink plenty of water to avoid heat-illness in these areas. Elsewhere, it will continue to be warm and muggy as well, with heat index values in the mid 80s to low 90s.

On Saturday, it will be warm and humid once again. Heat Index values look to stay just below advisory, but will likely be in the upper 80s to low 90s for many valley areas. Dewpoints will start to fall on Sunday as a cold front moves through the area, which should allow for a brief improvement in the heat index values for late in the weekend into early next week.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Through 18Z Saturday... VFR conditions prevail across all terminals through this afternoon with light and variable winds. There is potential for scattered thunderstorms across the region late this afternoon and this evening, reflected by PROB30 groups at all terminals. These storms could produce brief drops in vis/cigs to MVFR and IFR, with gusty winds up to 25-30 kts. Storm activity should subside by sunset, leaving light to calm winds. Lingering low-level moisture will allow patchy mist/fog and low clouds to develop overnight, dropping vis/cigs down to MVFR and IFR into the early morning hours on Saturday. Conditions are expected to rapidly clear after 12Z, with VFR conditions returning to all terminals. Light southwesterly to westerly winds are also expected to develop during this time period and persist through the end of the TAF period.

Outlook...

Saturday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Sunday: No Operational Impact. NO SIG WX. Sunday Night: No Operational Impact. NO SIG WX. Monday: Low Operational Impact. Slight Chance of SHRA...TSRA. Monday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Tuesday: Moderate Operational Impact. Chance of SHRA...TSRA. Tuesday Night: Moderate Operational Impact. Chance of SHRA. Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Heat Advisory until 8 PM EDT this evening for CTZ013. NY...Heat Advisory until 8 PM EDT this evening for NYZ064-065. MA...None. VT...None.